AQUARIUM EXPERIMENTS COMPARING THE FEEDING BEHAVIOUR OF ROCK LOBSTER JASUS LALANDII ON ABALONE AND SEA URCHINS AT TWO SITES ON THE WEST COAST OF SOUTH AFRICA

  • R F VAN ZYL Formerly Marine Biology Research Institute, Zoology Department, University of Cape Town, Rondebosch 7701, South Africa; now 1/19 Alpha Road, Prospect 5082, South Australia
  • S MAYFIELD Formerly Marine Biology Research Institute; now SARDI Aquatic Science, P.O. Box 120, Henley Beach 5022, South Australia
  • G M BRANCH Marine Biology Research Institute, Zoology Department, University of Cape Town.
Keywords: abalone Haliotis midae, Jasus lalandii, predation, sea urchins

Abstract

Predation by the rock lobster Jasus lalandii is influential in regulating the composition of shallow-reef communities on the west coast of South Africa. Two previous and independent studies addressing this topic, but conducted 600 km apart (one in Cape Town and the other in Port Nolloth on the west coast of South Africa) and using different experimental protocols, revealed contradictory results regarding the feeding behaviour of J. lalandii. The Port Nolloth study showed that juvenile abalone Haliotis midae hiding under sea urchins Parechinus angulosus were safe from predation by rock lobsters, which seemed to prefer the sea urchins as food. However, the Cape Town study showed that rock lobsters preferentially selected juvenile abalone over sea urchins. Because of the importance of these results to abalone ranching and the South African abalone fishery, the experiments were repeated at the two study sites, using a standardized experimental protocol. Rock lobsters from both sites showed a strong preference for juvenile abalone over sea urchins, even in the presence of kelp Ecklonia maxima. There was no significant difference (F3.92 = 0.09, p > 0.1) in abalone consumption by rock lobsters between the two sites. Therefore, at least in the absence of preferred prey such as mussels, sea urchins appear to provide only limited protection to juvenile abalone from rock lobsters.

Afr. J. mar. Sci. 25: 377–382
Published
2005-05-12
Section
Articles

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eISSN: 1814-2338
print ISSN: 1814-232X